1. Field of the Invention
The invention relates generally to an apparatus for separating a liquid component from a gaseous component. The invention relates more specifically to an apparatus for removing liquid particles entrained in a gaseous flow stream.
2. Description of the Related Art
Gas distribution systems, such as those used for the distribution of natural gas, employ pressure relief devices known as oil seals on the outlet side of regulator stations that feed low pressure gas systems. By design, when the pressure in the gas main exceeds the static pressure head of the oil in the oil seal, the oil is forced out of the lower chamber of the seal and into the upper chamber as the gas continues up a vent stack and exits out the top to the atmosphere. In practice, however, due to very high gas flow rates, the oil is atomized and carried out of the vent stack along with the gas. Since the oil used is typically kerosene, an emergency spill response is then needed to remove the oil from lawns, cars, and streets in the vicinity of the stack.
Since replacement of the oil seals with a different device is a costly alternative for even a portion of an entire gas distribution system, a solution is needed that prevents the kerosene from exiting the vent stack. Various conventional devices for effecting a liquid-from-fluid separation are known. For example, U.S. Pat. No. 735,192 describes a separator for removing oil or grease from fluids. The separator has a chamber (disclosed as being an upright cylinder), a baffle-plate in the form of an upright cylinder, and a drainage chamber, which is an annular chamber surrounding the baffle-plate. The separator uses spiral guides to guide the fluid along the inside of the cylindrical baffle-plate. The rotary motion imparted to the fluid by the spiral guides tends to throw out the minute particles of oil or grease and bring them into contact with the cylindrical baffle-plate.
U.S. Pat. No. 2,970,669 describes a condensing filter. The filter has a tubular body portion, a spiral member, and an absorbent wick. The wick absorbs fractions of gas which drain to it after condensing on the walls of the spiral passageway formed by the spiral member and the tubular body portion. The condensed fraction drains downwardly in the wick and is collected in the bottom of the separator.
U.S. Pat. No. 5,113,671 describes a device for separating oil from a gas. The separator has a housing forming a peripheral wall with an inlet at a top end of the housing for receiving an oil/gas mixture, a gas outlet formed by a conduit extending through the top end of the housing, and an oil outlet at a bottom end of the housing. Within the housing there is a static auger extending between a gas outlet conduit and the peripheral wall to cause the oil/gas mixture to flow in a largely circumferential path along the peripheral wall. Lining an inside surface of the housing is a means for collecting and separating oil, preferably in the form of a mesh screen. The collected oil drips from the screen to a baffle having apertures therein. The oil is received in an oil collection chamber below the baffle.
U.S. Pat No. 5,466,384 describes a device for carrying out phase separation by filtration and centrifugation. The device has a chamber with a filtration wall, such as a membrane, and a helical part. Discharge lines are provided for discharging respectively the permeate and retentate of the mixture to be separated.
Each of the above-described patents discloses a device that relies upon a spiral-type element to effect at least a portion of the separation. Various drawbacks are associated with the devices, however, including incomplete separation and the imposition of an unacceptably high back pressure for use in a gas distribution system.
Therefore, a need exists for an apparatus capable of removing a relatively small volume of liquid entrained in a gaseous stream having a high flow rate and velocity, yet without also imposing an unacceptably high back pressure to the gaseous stream.
The present invention provides an apparatus for removing liquid particles entrained in a gaseous flow stream. More specifically, the present invention provides an apparatus capable of removing a relatively small volume of liquid entrained in a gaseous stream having a high flow rate and velocity.
Accordingly, the present invention relates to a separator comprising a conduit disposed in a vertical orientation, a baffle axially disposed in the conduit, a wire mesh disposed circumferentially around the baffle, and an absorbant filter disposed circumferentially around the wire mesh. The entrained liquid-containing gaseous stream enters the separator through a separator first end, and exits the separator from a separator second end as an essentially liquid-free gaseous stream.
The invention also relates to a method of separating an entrained liquid from a gaseous stream with the separator. The method comprises passing the entrained liquid-containing gaseous stream through the separator first end, imparting a rotational flow to the entrained liquid-containing gaseous stream with the baffle, collecting the rotating liquid with the wire mesh so as to separate the entrained liquid from the gaseous stream, absorbing the collected liquid with the absorbant filter so as to produce an essentially liquid-free gaseous stream, and passing the essentially liquid-free gaseous stream from separator second end.
By virtue of using both centrifugal force and gravity to effect the separation of the entrained liquid particles, the separator can effect near-complete liquid removal in a gaseous stream flow rate of up to 70,000 cfh, yet without the imposition of any significant back pressure. Using the baffle, mesh, and filter to effect the separation, the separator is mechanically simple, and therefore relatively inexpensive to install and maintain.